Magnetic flux density

The magnetic flux density is a physical quantity that indicates the strength of the magnetic field at a particular point in space.

The magnitude of magnetic force on a moving charge is dependent on the magnetic flux density at a point.

The magnetic flux density $$B$$ is formally defined as the force per unit charge acting on a particle moving with a unit velocity in a direction perpendicular to the direction of a magnetic field.

$$$B=\frac{F_{\text{magnetic}}}{qv_{\text{perpendicular}}}$$$

$$q=$$charge of the particle moving with speed $$v_{\text{perpendicular}}$$ perpendicular to the magnetic field $$\vecphy{B}$$.

It is equivalent to the force per unit length acting on a straight conductor carrying a unit current placed perpendicular to the direction of a magnetic field (note that current is comprised of moving charges and is hence subject to magnetic forces).